Conventionally, a motor having a chucking unit for removably holding an optical disk such as a DVD or the like is provided with a circuit board through which an electric current is supplied to the coils of a stator. Along with the size reduction of a disk drive apparatus, attempts have been made to reduce the size of motor. The reduction in size of the motor makes it necessary to reduce the area of the circuit board. Furthermore, the reduction in price of the disk drive apparatus makes it inevitable to reduce the motor price.
As one approach to the motor price reduction, there is known a method by which the price of a circuit board is reduced by using only one surface of the circuit board. One example of the conventional motors that include a chucking unit and make uses of only one surface of a circuit board is disclosed in, e.g., Japanese Patent Laid-open Publication No. 10-248190.
In recent years, an increase in the writing speed of a disk leads to an increase in the rotation speed of a motor that holds the disk in place. One method of increasing the motor rotation speed is to increase the electric current supplied to coils. Since the space required in forming wiring lines of a circuit board is reduced along with the size reduction of the circuit board, however, it is impossible to increase the electric current supplied to the coils. In other words, the size reduction of the circuit board results in the reduction of a permissible current value in the wiring lines of the circuit board, thereby limiting the electric current supplied to the coils. In particular, since only one surface of the circuit board is used for the purpose of motor price reduction, the space required in forming the wiring lines is remarkably reduced by the size reduction of the circuit board. This makes it impossible to increase the rotation speed of the motor.